Turn Off Airplane Mode warning

[brunobowden]

Summary

The WHO App should show a similar warning to Facebook / WhatsApp for airplane mode. On iOS, those apps will show a user notification for "Turn Off Airplane Mode or Use Wi-Fi to Access Data", with links to "Settings" and "Ok".

Additional Context

I'm not sure how it does the airplane mode detection and what can be done on Android. Nonetheless, we should figure out the best we can do and implement that.

Screenshots

Screenshots

Checklist:

• [x] Searched the existing issues to ensure you are not creating a duplicate.
• [x] Followed the Contributor Guidelines.

[theswerd]

Do we have a preference between a CupertinoAlertDialog, AlertDialog(Material), a platform specific one, or one in our own style?

[brunobowden]

This is milestone v1.1. We should only focus on v1.0 until it’s launched.

[Henrymarks1]

@brunobowden Is this PR still relevant?